Interactive Acoustic Virtual Environments Using Distributed Room Acoustic Simulations

This publication presents how the computational resources of PC clusters can be used to realize low-latency room acoustic simulations for comprehensive virtual scenes. A benefit is not only to realize more complex scenes (including a multitude of sound sources, acoustically coupled-rooms with sound transmission), but also to minimize the system response times for prototyping applications (e.g. interactive change of materials or geometry) in simpler applications. PC clusters prove to be a suitable platform for room acoustic simulations, as the incorporated algorithms, the image source method and stochastic ray-tracing, are largely free of data interdependencies. For the computation in massive parallel systems the simulation of a room impulse response is separated into individual parts for the direct sound (DS), early reflections (ER) and diffuse late reverberation (LR). Additional decomposition concepts (e.g. individual image sources, frequency bands, sub volumes) are discussed. During user interaction (e.g. movement of the sources/listeners) the system is continuously issued new simulation tasks. A real-time scheduler decides on significant updates and assigns simulation tasks to available cluster nodes. Thereby the three simulation types are processed with different priorities. The multitude of (asynchronously) finished simulation tasks is transformed into room impulse responses. Convolution with the audio signals is realized by non-uniformly partitioned convolution in the frequency domain. The filter partitioning is adapted to the update rates of the individual impulse response parts (DS, ER,LR). Parallelization strategies, network protocols and performance figures are presented